Functional MRI (FMRI) with blood-oxygenation level dependent (BOLD) image-contrast provides unparalleled spatial resolution for mapping of human cerebral function. The BOLD image-contrast is determined by regional values of cerebral blood flow (CBF) and cerebral metabolic rate of oxygen consumption (CMRO). However, the relationship between BOLD image-contrast with CBF and CMR02 is not known quantitatively. Due to this uncertainty, to date, the BOLD method does not provide a direct measure of functional cortical activity. The objective of this proposal is to calibrate the BOLD signal with respect to blood oxygenation such that a high spatial resolution CMRO2 map can be obtained by combination of BOLD and CBF maps. By quantitative coregistration of CMR02 and CBF maps with autoradiographic maps of deoxyglucose consumption, during functional activation, the BOLD FMRI method will be converted into a technique that maps cortical activity. Applications of a quantitative BOLD FMRI method would include human brain mapping of sensory and cognitive functions, assessment of altered cortical activity in the diseased or injured brain, and long-term investigations of brain development and functional plasticity.